Polymer composition for the manufacture of thermoformed articles

ABSTRACT

This invention relates to a polymer composition that is particularly suitable for use in the manufacture of thermoformed articles, which can be biodegraded in industrial composting. This invention also relates to a process for the production of the said composition and articles obtained thereby.

DESCRIPTION

This invention relates to a polymer composition that is particularlysuitable for use in the manufacture of articles moulded by means ofthermoforming, which can be biodegraded in industrial composting.

This invention also relates to a process for the production of the saidcomposition and articles obtained thereby.

As is known, the techniques of hot moulding plastics materials, such asthermoforming, mainly find application in the production of articleshaving a high resistance to deformation, such as for example,containers, tubs, plates or capsules for the dispensing of beverages,with walls having thicknesses typically greater than 200 microns.

Thermoformed articles present on the market do not possess the necessaryproperties of disintegratability to render them suitable to be compostedin plants for industrial composting and resistance to deformation.

In view of the above it would be desiderable to have a compositioncapable of being transformed economically and productively intothermoformed articles, without adversely affecting compostability.

It has now surprisingly been discovered that it is possible to meet thisrequirement by means of a polymer composition for the production ofthermoformed articles comprising:

-   -   i) 20-60% by weight, preferably 30-50% by weight, with respect        to the sum of components i.-iv. of at least one polyester        comprising:        -   a) a dicarboxylic component comprising, with respect to            total dicarboxylic component:            -   a1) 0-20% in moles, preferably 0-10% in moles, of units                deriving from at least one aromatic dicarboxylic acid,            -   a2) 80-100% in moles, preferably 90-100% in moles, of                units deriving from at least one saturated aliphatic                dicarboxylic acid,            -   a3) 0-5% in moles, preferably 0.1-1% in moles, more                preferably 0.2-0.7% in moles, of units deriving from at                least one unsaturated aliphatic dicarboxylic acid;        -   b) a diol component comprising, with respect to total diol            component:            -   b1) 95-100% in moles, preferably 97-100% in moles, of                units deriving from at least one saturated aliphatic                diol;            -   b2) 0-5% in moles, preferably 0-3% in moles, of units                deriving from at least one unsaturated aliphatic diol;    -   ii) 5-35% by weight, preferably 10-20% by weight, with respect        to the sum of components i.-iv., of at least one        polyhydroxyalkanoate;    -   iii) 0.01-5% by weight, preferably 0.02-3% by weight, with        respect to the sum of components i.-iv., of at least one        cross-linking agent and/or a chain extender comprising at least        one compound having di- and/or multiple functional groups        comprising isocyanate, peroxide, carbodiimide, isocyanurate,        oxazoline, epoxy, anhydride or divinyl ether groups and mixtures        thereof;    -   iv) 5-50% by weight, preferably 10-40% by weight, with respect        to the sum of components i.-iv., of at least one mineral filler        agent, present in the form of particles having a median diameter        of less than 1.5 microns.

With regard to the polyesters of the composition according to thisinvention, these comprise a dicarboxylic component which comprises, withrespect to total dicarboxylic component, 0-20% in moles, preferably0-10% in moles of units deriving from at least one aromatic dicarboxylicacid and 80-100% in moles, preferably 90-100% in moles of units derivingfrom at least one saturated aliphatic dicarboxylic acid and 0-5% inmoles, preferably 0.1-1% in moles, more preferably 0.2-0.7% in moles, ofunits deriving from at least one unsaturated aliphatic dicarboxylicacid.

The aromatic dicarboxylic acids are preferably selected from aromaticdicarboxylic acids of the phthalic acid type, preferably terephthalicacid or isophthalic acid, more preferably terephthalic acid, andheterocyclic dicarboxylic acids, preferably 2,5-furandicarboxylic acid,2,4-furandicarboxylic acid, 2,3-furandicarboxylic acid,3,4-furandicarboxylic acid, more preferably 2,5-furandicarboxylic acid,their esters, their salts and their mixtures. In a preferred embodimentthe said aromatic dicarboxylic acids comprise:

-   -   from 1 to 99% in moles, preferably from 5 to 95% and more        preferably from 10 to 80%, of terephthalic acid, its esters or        its salts;    -   from 99 to 1% in moles, preferably from 95 to 5% and more        preferably from 90 to 20%, of 2,5-furandicarboxylic acid, its        esters or its salts.

The saturated aliphatic dicarboxylic acids are preferably selected fromC₂-C₂₄, preferably C₄-C₁₃, more preferably C₄-C₁₁, saturateddicarboxylic acids their C₁-C₂₄, preferably C₁-C₄, alkyl esters, theirsalts and their mixtures.

Preferably the saturated aliphatic dicarboxylic acids are selected from:succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaricacid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacicacid, undecandioic acid, dodecandioic acid, brassylic acid and theirC₁₋₂₄ alkyl esters.

In a preferred embodiment of this invention the saturated aliphaticdicarboxylic acids comprise mixtures comprising at least 50% in moles,preferably more than 60% in moles, more preferably more than 65% inmoles of succinic acid, adipic acid, azelaic acid, sebacic acid,brassylic acid, their C₁-C₂₄, preferably C₁-C₄, esters and theirmixtures.

The unsaturated aliphatic dicarboxylic acids are preferably selectedfrom itaconic acid, fumaric acid, 4-methylene-pimelic acid, 3,4-bis(methylene) nonandioic acid, 5-methylene-nonandioic acid, their C₁-C₂₄,preferably C₁-C₄, alkyl esters, their salts and their mixtures. In apreferred embodiment of this invention the unsaturated aliphaticdicarboxylic acids comprise mixtures comprising at least 50% in moles,preferably more than 60% in moles, more preferably more than 65% inmoles of itaconic acid, its C₁-C₂₄, preferably C₁-C₄ esters. Morepreferably, the unsaturated aliphatic dicarboxylic acids compriseitaconic acid.

The diol component of the polyesters of the composition according tothis invention comprises 95-100% in moles, preferably 97-100% in moles,of units deriving from at least one saturated aliphatic diol, withrespect to total diol component, and 0-5% in moles, preferably 0-3% inmoles, with respect to total diol component, of units deriving from atleast one unsaturated aliphatic diol.

In a preferred embodiment, the diol component of the polyesters of thecomposition according to this invention consists of saturated aliphaticdiols.

With regard to the saturated aliphatic diols, these are preferablyselected from 1,2-ethandiol, 1,2-propandiol, 1,3-propandiol,1,4-butandiol, 1,5-pentandiol, 1,6-hexandiol, 1,7-heptandiol,1,8-octandiol, 1,9-nonandiol, 1,10-decandiol, 1,11-undecandiol,1,12-dodecandiol, 1,13-tridecandiol, 1,4-cyclohexandimethanel,neopentylglycol, 2-methyl-1,3-propandiol, dianhydrosorbitol,dianhydromannitol, dianhydroiditol, cyclohexandiol,cyclohexanmethandiol, dialkyleneglycols and polyalkylene glycols with amolecular weight of 100-4000, such as for example polyethylene glycol,polypropylene glycol and their mixtures. Preferably the diol componentcomprises at least 50% in moles of one or more diols selected from1,2-ethandiol, 1,3-propandiol, 1,4-butandiol. More preferably the diolcomponent comprises, or consists of, 1,4-butandiol.

With regard to the unsaturated aliphatic diols these are preferablyselected from cis 2-buten-1,4-diol, trans 2-buten-1,4-diol,2-butyn-1,4-diol, cis 2-penten-1,5-diol, trans 2-penten-1,5-diol,2-pentyn-1,5-diol, cis 2-hexen-1,6-diol, trans 2-hexen-1,6-diol,2-hexyn-1,6-diol, cis 3-hexen-1,6-diol, trans 3-hexen-1,6-diol,3-hexyn-1,6-diol.

With regard to polyesters i. in the composition, these are preferablyselected from aliphatic polyesters (“AP”) and aliphatic-aromaticpolyesters (“AAPE”).

In the meaning of this invention, by aliphatic polyesters AP are meantpolyesters comprising a dicarboxylic component which consists, withrespect to the total moles of the dicarboxylic component, of 95-100% inmoles of at least one saturated aliphatic dicarboxylic acid and 0-5% inmoles of at least one unsaturated aliphatic dicarboxylic acid, and adiol component comprising, with respect to the total moles of the diolcomponent, 95-100% in moles of units deriving from at least onesaturated aliphatic diol and 0-5% in moles of units deriving from atleast one unsaturated aliphatic diol.

By AAPE polyesters, in this invention are meant polyesters comprising adicarboxylic component which consists at least one aromatic dicarboxylicacid compound, at least one saturated aliphatic dicarboxylic acid and0-5% in moles, with respect to the total moles of the dicarboxyliccomponent, of at least one unsaturated aliphatic dicarboxylic acid and adiol component comprising, with respect to the total moles of the diolcomponent, 95-100% in moles of units deriving from at least onesaturated aliphatic diol and 0-5% in moles of units deriving from atleast one unsaturated aliphatic diol.

In the case of the AP aliphatic polyesters, those preferred arepolyesters in which the dicarboxylic component comprises units derivingfrom at least one C₂-C₂₄, preferably C₄-C₁₃, more preferably C₄-C₁₁saturated aliphatic dicarboxylic acid, their C₁-C₂₄, preferably C₁-C₄alkyl esters, their salts and their mixtures, and a diol componentcomprising units deriving from at least one saturated aliphatic diol,preferably selected from 1,2-ethandiol, 1,2-propandiol, 1,3-propandiol,1,4-butandiol.

In a preferred embodiment of this invention, polyester i. of thecomposition comprises at least one aliphatic polyester (AP), preferablypoly(1,4-butylene succinate), poly(1,4-butylene adipate), poly(1,4-butylene azelate), poly(1,4-butylene sebacate), poly(1,4-butyleneadipate-co-1,4-butylene succinate), poly(1,4-butyleneazelate-co-1,4-butylene succinate), poly(1,4-butylenesebacate-co-1,4-butylene succinate), poly(1,4-butylenesuccinate-co-1,4-butylene adipate-co-1,4-butylene azelate). In aparticularly preferred embodiment the said aliphatic polyester ispoly(1,4-butylene succinate).

In a further preferred embodiment of this invention the polyester of thecomposition comprises at least one aliphatic-aromatic polyester (AAPE),and is advantageously selected from:

-   -   (A) polyesters comprising repetitive units deriving from        aromatic dicarboxylic acids of the phthalic acid type,        preferably terephthalic acid, aliphatic dicarboxylic acids and        aliphatic diols (AAPE-A), characterised by an aromatic units        content of between 35 and 60% in moles, preferably between 40        and 55% in moles with respect to the total moles of the        dicarboxylic component. The AAPE-A polyesters are preferably        selected from: poly(1,4-butylene adipate-co-1,4-butylene        terephthalate), poly(1,4-butylene sebacate-co-1,4-butylene        terephthalate), poly(1,4-butylene azelate-co-1,4-butylene        terephthalate), poly(1,4-butylene brassylate-co-1,4-butylene        terephthalate), poly(1,4-butylene succinate-co-1,4-butylene        terephthalate), poly(1,4-butylene adipate-co-1,4-butylene        sebacate-co-1,4-butylene terephthalate), poly(1,4-butylene        azelate-co-1,4-butylene sebacate-co-1,4-butylene terephthalate),        poly(1,4-butylene adipate-co-1,4-butylene        azelate-co-1,4-butylene terephthalate), poly(1,4-butylene        succinate-co-1,4-butylene sebacate-co-1,4-butylene        terephthalate), poly(1,4-butylene adipate-co-1,4-butylene        succinate-co-1,4-butylene terephthalate). poly(1,4-butylene        azelate-co-1,4-butylene succinate-co-1,4-butylene        terephthalate).    -   (B) polyesters comprising repetitive units deriving from        heterocyclic dicarboxylic acids, preferably        2,5-furandicarboxylic acid, aliphatic dicarboxylic acids and        aliphatic diols (AAPE-B), characterised by an aromatic units        content of between 50 and 80% in moles, preferably of between 60        and 75% in moles with respect to the total moles of the        dicarboxylic component. The AAPE-B polyesters are preferably        selected from: poly(1,4-butylene adipate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        sebacate-co-1,4-butylene 2,5-furandicarboxylate),        poly(1,4-butylene azelate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        brassylate-co-1,4-butylene 2,5-furandicarboxylate),        poly(1,4-butylene succinate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        adipate-co-1,4-butylene sebacate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        azelate-co-1,4-butylene sebacate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        adipate-co-1,4-butylene azelate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        succinate-co-1,4-butylene sebacate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        adipate-co-1,4-butylene succinate-co-1,4-butylene        2,5-furandicarboxylate), poly(1,4-butylene        azelate-co-1,4-butylene succinate-co-1,4-butylene        2,5-furandicarboxylate).

In addition to the dicarboxylic component and the diol component, thepolyesters of the composition according to this invention preferablycomprise repetitive units deriving from at least one hydroxy acid in aquantity of between 0 and 49%, preferably between 0 and 30% in moleswith respect to the total moles of the dicarboxylic component. Examplesof convenient hydroxyacids are glycolic, hydroxybutyric, hydroxycaproic,hydroxyvaleric, 7-hydroxyheptanoic, 8-hydroxycaproic, 9-hydroxynonanoicand lactic acids or lactides. The hydroxyacids may be inserted in thechain as such or may also be first caused to react with diacids ordiols.

Long molecules with two functional groups including functional groupswhich are not in a terminal position may also be present in quantitiesof not more than 10% in moles with respect to the total moles of thedicarboxylic component. Examples are dimer acids, ricinoleic acid andacids incorporating epoxy functional groups and also polyoxyethyleneswith molecular weights of between 200 and 10000.

Diamines, aminoacids and aminoalcohols may also be present inpercentages up to 30% in moles with respect to the total moles of thedicarboxylic component.

During preparation of the polyesters of the composition according tothis invention one or more molecules with multiple functional groups inquantities of between 0.1 and 3% in moles with respect to the totalmoles of the dicarboxylic component (as well as any hydroxyacids) mayalso advantageously be added in order to obtain branched products.Examples of these molecules are glycerol, pentaerythritol,trimethylolpropane, citric acid, dipentaerythritol, acid triglycerides,polyglycerols.

The molecular weight Mn of the polyesters of the composition accordingto this invention is preferably ≥20000, more preferably ≥40000. As faras the polydispersity index of the molecular weights Mw/Mn is concerned,this is instead preferably between 1.5 and 10, more preferably between1.6 and 5 and even more preferably between 1.8 and 2.7.

The molecular weights M_(n) and M_(w) may be measured by means of GelPermeation Chromatography (GPC). The determination may be performed withthe cromatography system maintained at 40° C., using a set of threecolumns in series (particle diameter 5 μm and porosities of 500 Å, 10000Å and 100000 Å) respectively, a refractive index detector, chloroform aseluent (flow 1 ml/min) and using polystyrene as the reference standard.

The terminal acid groups content of the polyesters of the compositionaccording to this invention is preferably between 20 and 160 meq/kg.

The terminal acid groups content may be measured in the following way:1.5-3 g of the polyester are placed in a 100 ml flask together with 60ml of chloroform. After the polyester has completely dissolved 25 ml of2-propanol are added and, immediately before the analysis, 1 ml ofdeionised water. The solution so obtained is titrated against apreviously standardised solution of NaOH in ethanol. An appropriateindicator, such as for example a glass electrode for acid-basetitrations in non-aqueous solvents, is used to determine the end pointof the titration. The terminal acid groups content is calculated on thebasis of the NaOH solution in ethanol consumed using the followingequation:

${{Terminal}\mspace{14mu} {acid}\mspace{14mu} {groups}\mspace{14mu} {content}\mspace{14mu} ( {{meq}\text{/}{kg}\mspace{14mu} {polymer}} )} = \frac{\lfloor {( {V_{eq} - V_{b}} ) \cdot T} \rfloor \cdot 1000}{P}$

in which: V_(eq)=ml of NaOH in ethanol solution at the end point of thetitration of the sample;

-   -   Y_(b)=ml of NaOH in ethanol solution required to achieve a        pH=9,5 during the blank titration;    -   T=concentration of the solution of NaOH in ethanol expressed in        moles/litre;    -   P=weight of the sample in grams.

Preferably, the polyesters of the composition according to thisinvention have an inherent viscosity (measured with an Ubbelohdeviscometer for solutions in CHCl₃ of concentration 0.2 g/dl at 25° C.)of more than 0.3 dl/g, preferably between 0.3 and 2 dl/g, morepreferably between 0.4 and 1.3 dl/g.

Preferably, the polyesters of the composition according to thisinvention are biodegradable. In the meaning of this invention, bybiodegradable polymers are meant polymers which are biodegradableaccording to standard EN 13432.

The polyesters of the composition according to this invention may besynthesised by any of the processes known in the art. In particular,they may advantageously be obtained through a polycondensation reaction.

Advantageously the synthesis process may be performed in the presence ofa suitable catalyst. Among such suitable catalysts mention may, by wayof example, be made of organometallic compounds of tin, for examplederivatives of stannoic acid, titanium compounds, for example orthobutyltitanate, aluminium compounds, for example Al-triisopropyl, compounds ofantimony and zinc and zirconium and mixtures thereof.

In order to ensure high properties of resistance to deformation for thethermoformed articles, the composition according to this inventioncomprises 5-35% by weight, preferably 10-20% by weight, with respect tothe sum of components i.-iv., of at least one polyhydroxyalkanoate(component ii.) preferably selected from the group comprising thepolyesters of lactic acid, poly-ε-caprolactone, polyhydroxybutyrate,polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate,polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate,polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate,polyhydroxybutyrate-octadecanoate, poly3-hydroxybutyrate-4-hydroxybutyrate. Preferably the polyhydroxyalkanoateof the composition comprises at least 80% by weight of one or morepolyesters of lactic acid.

In a preferred embodiment the polyesters of lactic acid are selectedfrom the group which comprises poly L lactic acid, poly D lactic acid,poly D-L lactic acid stereo complex, copolymers comprising more than 50%in moles of the said polyesters of lactic acid or their mixtures.

The polyesters of lactic acid containing at least 95% by weight ofrepetitive units deriving from L-lactic or D-lactic acid or theircombinations, with a molecular weight Mw of more than 50,000 and with ashear viscosity of between 50 and 500 Pa·s, preferably between 100 and300 Pa·s (measured according to standard ASTM D3835 at T=190° C., shearrate=1000s⁻¹, D=1 mm, L/D=10), are particularly preferred.

In a particularly preferred embodiment of the invention, the polyesterof lactic acid comprises at least 95% by weight of units deriving fromL-lactic acid, ≤5% of repetitive units deriving from D-lactic acidhaving a melting point in the range 135-170° C., a glass transitiontemperature (Tg) in the range 55-65° C. and an MFR (measured accordingto standard ASTM-D1238 at 190° C. and 2.16 kg) in the range 1-50 g/10min. Commercial examples of polyesters of lactic acid having theseproperties are for example products of the Ingeo™ trade mark Biopolymer4043D, 3251D and 6202D.

The composition according to this invention comprises 0.01-5% by weight,preferably 0.02-3% by weight, more preferably 0.1-1% by weight, of atleast one cross-linking agent and/or chain extender (component iii.)which improves stability to hydrolysis and is selected from compoundshaving di- and/or multiple functional groups incorporating isocyanate,peroxide, carbodiimide, isocyanurate, oxazoline, epoxy, anhydride ordivinyl ether groups and mixtures thereof.

Preferably, the cross-linking agent and/or chain extender comprises atleast one compound having di- and/or multiple functional groupscomprising isocyanate groups. More preferably the cross-linking agentand/or chain extender comprises at least 25% by weight of one or morecompounds having di- and/or multiple functional groups incorporatingisocyanate groups.

Particularly preferred are mixtures of compounds having di- and/ormultiple functional groups incorporating isocyanate groups withcompounds having di- and/or multiple functional groups incorporatingepoxy groups, even more preferably comprising at least 75% by weight ofcompounds having di- and/or multiple functional groups incorporatingisocyanate groups.

The compounds having di- and multiple functional groups incorporatingisocyanate groups are preferably selected from p-phenylene diisocyanate,2,4-toluene diisocyanate, 2,6-toluene diisocyanate,4,4-diphenylmethane-diisocyanate, 1,3-phenylene-4-chloro diisocyanate,1,5-naphthalene diisocyanate, 4,4-diphenylene diisocyanate,3,3′-dimethyl-4,4diphenylmethane diisocyanate,3-methyl-4,4′-diphenylmethane diisocyanate, diphenylester diisocyanate,2,4-cyclohexane diisocyanate, 2,3-cyclohexane diisocyanate, 1-methyl2,4-cyclohexyl diisocyanate, 1-methyl 2,6-cyclohexyl diisocyanate,bis-(isocyanate cyclohexyl) methane, 2,4,6-toluene triisocyanate,2,4,4-diphenylether triisocyanate,polymethylene-polyphenyl-polyisocyanates, methylene diphenyldiisocyanate, triphenylmethane triisocyanate,3,3′ditolylene-4,4-diisocyanate, 4,4′-methylenebis (2-methyl-phenylisocyanate), hexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate,1,2-cyclohexylene diisocyanate and their mixtures. In a preferredembodiment, the compound comprising isocyanate groups is4,4-diphenylmethane-diisocyanate.

With regard to compounds having di- and multiple functional groupsincorporating peroxide groups, these are preferably selected frombenzoyl peroxide, lauroyl peroxide, isononanoyl peroxide,di-(t-butylperoxyisopropyl)benzene, t-butyl peroxide, dicumyl peroxide,alpha,alpha′-di(t-butylperoxy)diisopropylbenzene,2,5-dimethyl-2,5di(t-butylperoxy)hexane, t-butyl cumyl peroxide,di-t-butylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hex-3-yne,di(4-t-butylcyclohexyl)peroxy dicarbonate, dicetyl peroxydicarbonate,dimyristyl peroxydicarbonate,3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, di(2-ethylhexyl)peroxydicarbonate and their mixtures.

The compounds having di- and multiple functional groups incorporatingcarbodiimide groups which are preferably used in the compositionaccording to this invention are preferably selected frompoly(cyclooctylene carbodiimide), poly(1,4-dimethylenecyclohexylenecarbodiimide), poly(dicyclohexylmethane carbodiimide),poly(cyclohexylene carbodiimide), poly(ethylene carbodiimide),poly(butylene carbodiimide), poly(isobutylene carbodiimide),poly(nonylene carbodiimide), poly(dodecylene carbodiimide),poly(neopentylene carbodiimide), poly(1,4-dimethylene phenylenecarbodiimide), poly(2,2′,6,6′-tetraisopropyldiphenylene carbodiimide)(Stabaxol® D), poly(2,4,6-triisolpropyl-1,3-phenylene carbodiimide)(Stabaxol® P-100), poly(2,6 diisopropyl-1,3-phenylene carbodiimide)(Stabaxol® P), poly (tolyl carbodiimide), poly(4,4′-diphenylmethanecarbodiimide), poly(3,3′-dimethyl-4,4′-biphenylene carbodiimide),poly(p-phenylene carbodiimide), poly(m-phenylene carbodiimide),poly(3,3′-dimethyl-4,4′-diphenylmethane carbodiimide), poly(naphthylenecarbodiimide), poly(isophorone carbodiimide), poly(cumene carbodiimide),p-phenylene bis(ethylcarbodiimide), 1,6-hexamethylenebis(ethylcarbodiimide), 1,8-octamethylene bis(ethylcarbodiimide),1,10-decamethylene bis(ethylcarbodiimide), 1,12 dodecamethylenebis(ethylcarbodiimide) and their mixtures.

Examples of compounds having di- and multiple functional groupsincorporating epoxy groups which may advantageously be used in thecomposition according to this invention are all the polyepoxides fromepoxydised oils and/or styrene-glycidylether-methylmethacrylate,glycidylether methylmethacrylate, included in a range of molecularweights between 1000 and 10000 and having an epoxy number per moleculein the range from 1 to 30 and preferably between 5 and 25, and theepoxides selected from the group comprising: diethylene glycoldiglycidylether, polyethylene glycol diglycidyl ether, glycerolpolyglycidyl ether, diglycerol polyglycidyl ether, 1,2-epoxybutane,polyglycerol polyglycidyl ether, isoprene diepoxy and cycloaliphaticdiepoxides, 1,4-cyclohexandimethanol diglycidyl ether, glycidyl2-methylphenyl ether, glycerol propoxylatotriglycidyl ether,1,4-butandiol diglycidyl ether, sorbitol polyglycidyl ether, glyceroldiglycidyl ether, tetraglycidyl ether of meta-xylenediamine and thediglycidyl ether of bisphenol A and their mixtures.

Together with the compounds having di- and multiple functional groupsincorporating isocyanate, peroxide, carbodiimide, isocyanurate,oxazoline, epoxy, anhydride and divinylether groups of the compositionaccording to this invention, catalysts may be also used to increase thereactivity of the reactive groups. In the case of polyepoxides, salts offatty acids, even more preferably calcium and zinc stearates, arepreferably used.

In a particularly preferred embodiment of the invention thecross-linking agent and/or chain extender of the composition comprisescompounds incorporating isocyanate groups, preferably4,4-diphenylmethane-diisocyanate, and/or incorporating carbodiimidegroups, and/or incorporating epoxy groups, preferably of thestyrene-glycidylether-methylmethacrylate type.

The composition according to this invention comprises 5-50% by weight,preferably 10-40% by weight, of at least one mineral filler agent(component iv.), present in the form of particles having a mediandiameter of less than 1.5 microns. preferably of less than 1.2 microns,wherein the particle size distribution is measured by Sedigraphaccording to ISO 13317-3. It has in fact been discovered that themineral filler agents characterised by the said median diameter improvethe resistance to deformation, the dimensional stability as well as thedisintegratability properties of the thermoformed articles comprisingthe polymer composition according to this invention. Preferably, thethermoformed articles are characterised by G′ modulus values, obtainedat 70° C. through dynamic mechanical-torsional analysis (DMTA), higherthan 180, preferably higher than 230 MPa, and G′ modulus values,obtained at 90° C. through DMTA, higher than 125, preferably higher than150 MPa.

In a preferred embodiment of this invention, the thermoformed articlesare characterised by of G′ modulus values obtained at 70° C. higher than300 MPa, and values of G′ obtained at 90° C. higher than 200 MPa.

Preferably, the mineral filler agent is selected from talc, carbonatesof calcium and titanium dioxide. In a particularly preferred embodimentthe said mineral filler agent is talc.

Without being bound thereby to any specific theory, it is felt that thesaid mineral filler agents, when used in the compositions according tothe invention, become stratified and agglomerate during the mouldingstage, thus slowing the action of the agents responsible for thedisintegration of the thermoformed articles.

In addition to components i.-iv. the composition according to thisinvention preferably also contains at least one other component selectedfrom the group consisting of plasticisers, UV stabilisers, lubricants,nucleating agents, surfactants, antistatic agents, pigments, flameretardants, compatibilising agents, lignin, organic acids, antioxidants,mould prevention agents, waxes, process coadjuvants and polymercomponents preferably selected from the group consisting of vinylpolymers, polyesters of diacid diols which are other than polyester i.,polyamides, polyurethanes, polyethers, polyureas and polycarbonates.

With regard to plasticisers, in addition to the plasticisers preferablyused for the preparation of destructured starch described above, thereare preferably present in the composition according to this inventionone or more plasticisers selected from the group comprising phthalates,such as for example diisononyl phthalate, trimellitates, such as forexample the esters of trimellitic acid with C₄-C₂₀ monoalcoholspreferably selected from the group comprising n-octanol and n-decanol,and aliphatic esters having the following structure:

R₁—O—C(O)—R₄—C(O)—[—O—R₂—O—C(O)—R₅—C(O)-]_(m)—O—R₃

in which:

-   -   R₁ is selected from one or more of the groups comprising H,        linear and branched saturated and unsaturated alkyl residues of        the C₁-C₂₄ type, polyol residues esterified with C₁-C₂₄        monocarboxylic acids;    -   R₂ comprises —CH₂—C(CH₃)₂—CH₂— and alkylene C₂-C₈, groups and        comprises at least 50% in moles of the said —CH₂—C(CH₃)₂—CH₂—        groups;    -   R₃ is selected from one or more of the groups comprising H,        linear and branched saturated and unsaturated alkyl residues of        the C₁-C₂₄ type, polyol residues esterified with C₁-C₂₄        monocarboxylic acids;    -   R₄ and R₅ are the same or different, comprise one or more C₂        ⁻C₂₂, preferably C₂-C₁₁, more preferably C₄-C₉ alkylenes and        comprise at least 50% in moles of C₇ alkylenes.

m is a number between 1 and 20, preferably 2-10, more preferably 3-7.Preferably, in the said esters at least one of the R₁ and/or R₃ groupscomprises, preferably in quantities ≥10% in moles, more preferably ≥20%,even more preferably ≥25% in moles with respect to the total quantitiesof R₁ and/or R₃ groups, polyol residues esterified with at least oneC₁-C₂₄ monocarboxylic acid selected from the group comprising stearicacid, palmitic acid, 9-ketostearic acid, 10-ketostearic acid andmixtures thereof. Examples of aliphatic esters of this type aredescribed in Italian patent application MI2014A000030 and PCTapplications PCT/EP2015/050336, PCT/EP2015/050338.

When present, the selected plasticisers are preferably present up to 10%by weight, with respect to the total weight of the composition.

The lubricants are preferably selected from esters and metal salts offatty acids such as for example zinc stearate, calcium stearate,aluminium stearate and acetyl stearate. Preferably the compositionaccording to this invention comprises up to 1% by weight of lubricants,more preferably up to 0.5% by weight, with respect to the total weightof the composition.

Examples of nucleating agents include the sodium salt of saccharine,calcium silicate, sodium benzoate, calcium titanate, boron nitride,isotactic polypropylene, low molecular weight PLA. These additives arepreferably added in quantities up to 10% by weight and more preferablybetween 2 and 6% by weight with respect to the total weight of thecomposition.

Pigments may also be added if necessary, for example titanium dioxide,clays, copper phthalocyanin, titanium dioxide, silicates, oxides andhydroxides of iron, carbon black and magnesium oxide. These additiveswill preferably be added up to 10% by weight.

Among the vinyl polymers, those preferred are: polyethylene,polypropylene, their copolymers, polyvinyl alcohol, polyvinyl acetate,polyethyl vinyl acetate and polyethylene vinyl alcohol, polystyrene,chlorinated vinyl polymers, polyacrylates.

Among the chlorinated vinyl polymers these are here intended to includein addition to polyvinyl chloride: polyvinylidene chloride, polyethylenechloride, poly(vinyl chloride-vinyl acetate), poly(vinylchloride-ethylene), poly(vinyl chloride-propylene), poly(vinylchloride-styrene), poly(vinyl chloride-isobutylene) and copolymers inwhich polyvinyl chloride represents more than 50% in moles. The saidcopolymers may be random, block or alternating.

With regard to the polyamides of the composition according to thisinvention, these are preferably selected from the group consisting ofpolyamide 6 and 6,6, polyamide 9 and 9,9, polyamide 10 and 10,10,polyamide 11 and 11,11, polyamide 12 and 12,12 and their combinations ofthe 6/9, 6/10, 6/11, 6/12 type, their mixtures and both random and blockcopolymers.

Preferably the polycarbonates of the composition according to thisinvention are selected from the group comprising polyalkylenecarbonates, more preferably polyethylene carbonates, polypropylenecarbonates, polybutylene carbonates, their mixtures and copolymers bothrandom and block copolymers.

Among the polyethers, those preferred are those selected from the groupconsisting of polyethylene glycols, polypropylene glycols, polybutyleneglycols their copolymers and their mixtures with molecular weights from70,000 to 500,000.

With regard to polyesters of diacid diols which are other than polyesteri., these preferably comprise:

-   -   a) a dicarboxylic component comprising, with respect to the        total dicarboxylic component:        -   a1) 20-100% in moles of units deriving from at least one            aromatic dicarboxylic acid,        -   a2) 0-80% in moles of units deriving from at least one            saturated aliphatic dicarboxylic acid,        -   a3) 0-5% in moles of units deriving from at least one            unsaturated aliphatic dicarboxylic acid;    -   b) a diol component comprising, with respect to the total diol        component:        -   b1) 95-100% in moles of units deriving from at least one            saturated aliphatic diol;        -   b2) 0-5% in moles of units deriving from at least one            unsaturated aliphatic diol.

Preferably, the aromatic dicarboxylic acids, saturated aliphaticdicarboxylic acids, unsaturated aliphatic dicarboxylic acids, saturatedaliphatic diols and unsaturated aliphatic diols for the said polyestersare selected from those described above for the polyester (component i.)of the composition according to this invention. More preferably the saiddiacid-diol polyesters which are other than polyester i. are selectedfrom the group consisting of poly(ethylene terephthalate),poly(propylene terephthalate), poly(butylene terephthalate),poly(ethylene 2,5 furandicarboxylate), poly(propylene2,5-furandicarboxylate), poly(butylene 2,5-furandicarboxylate) and blockor random copolymers of the poly(alkylene2,5-furandicarboxylate-co-alkylene terephthalate) type.

The production of the polymer composition according to this inventioncan be carried out by any of the processes known in the art.Advantageously the polymer composition according to this invention isproduced by means of extrusion processes in which the polymer componentsare mixed in the fused state. In extruding the composition thecomponents may be fed all together or one or more of them may be fedseparately along the extruder.

This invention also relates to thermoformed articles, comprising thesaid polymer composition, which in fact has processability andperformance in use properties which render it particularly suitable forthis use. Its properties in fact make it possible to manufacturethermoformed articles having good resistance to deformation, highdimensional stability and bend temperature under load properties whichare able to disintegrate and biodegrade in industrial compostingprocesses.

Preferably, thermoformed articles, comprising the composition accordingto this invention, are biodegradable according to EN 13432, when havingthickness up to 250 μm.

For example the polymer composition according to the invention isparticularly suitable for the manufacture thermoformed articles such asfor example, plates and cups, rigid containers, capsules for thedispensing of beverages, preferably hot beverages, lids and covers, andfood packaging which can be heated in conventional and microwave ovens.The composition according to this invention and the thermoformedarticles it comprises are preferably characterised by a THF content ofbelow 10 mg/kg, preferably <5 mg/kg, and are capable of being used incontact with food, as occurs for example in the case of capsules for thedispensing of beverages. In a preferred embodiment this inventionrelates to a capsule for the dispensing of beverages characterised by aTHF content of below 3 mg/kg, preferably 1 mg/kg. In the case of thecompositions which comprise polyesters comprising 1,4-butylenedicarboxylate units as component i. the said low THF content can beobtained by subjecting the compositions according to this invention, orthe thermoformed articles comprising them, to at least one stage ofvolatilisation of the THF.

In a preferred embodiment of this invention the said thermoformedarticles comprise at least one layer A comprising the compositionaccording to this invention and at least one layer B comprising at leastone polymer selected from the group comprising diacid-diol polyestersand hydroxy acid polyesters, and are preferably characterised by amutual arrangement of the said layers A and B selected from A/B, A/B/Aand B/A/B. In a further particularly preferred embodiment the said layerB consists of a polyester of lactic acid.

As far as the process of moulding by means of thermoforming isconcerned, the polymer composition according to this invention may bethermoformed by means of methods known to those skilled in the art, fromfor example from sheets or film, under pressure or under vacuum. Thisinvention also relates to the said sheets or film comprising thecomposition according to this invention, used for the production ofmoulded articles by means of thermoforming.

Typical operating conditions for thermoforming provide for example atime of 5-8 seconds for heating the said sheets or film until theysoften, and moulding times of between 15 and 20 seconds.

The invention will now be illustrated through a number embodiments whichare intended to be by way of example and do not limit the scope ofprotection of this patent application.

EXAMPLES

Component i

-   -   i-1 =Poly(1,4-butylene succinate) (“PBS”) prepared according to        the following method:        -   17150 g of succinic acid, 14000 g of 1,4-butandiol, 26.75 g            of glycerine and 2.0 g of an 80% by weight ethanolic            solution of diisopropyl triethanolamine titanate (Tyzor TE,            containing 8.2% by weight of titanium) were added to a steel            reactor having a geometrical capacity of 40 litres fitted            with a mechanical stirring system, an inlet for nitrogen, a            distillation column, a knock-down system for high boiling            point components and a connection to a high vacuum system in            a diol/dicarboxylic acid (MGR) molar ratio of 1.08.        -   The temperature of the mass was gradually raised to 230° C.            over a period of 120 minutes. When 95% of the theoretical            water has been distilled off, 21.25 g of tetra n-butyl            titanate (corresponding to 119 ppm of metal with respect to            the quantities of polyl,4-butylene succinate that would be            theorically obtainable by converting all the succinic acid            fed to the reactor) were added. The temperature of the            reactor was then raised to 235-240° C. and the pressure was            gradually reduced to a value below 2 mbar over a period of            60 minutes. The reaction was allowed to proceed for the time            required to obtain a poly(1,4-butylene succinate) with an            MFR of approximately 7 (g/10 minutes at 190° C. and 2.16            kg), and the material was then discharged in the form of a            filament into a water bath and granulated.    -   i-2=Poly(1,4-butylene sebacate-co-1,4-butylene terephthalate)        (“PBST”) was prepared according to the following method: 8160 g        of terephthalic acid, 11198 g of sebacic acid, 11296 g of        1,4-butanediol, 14.4 g of glycerine and 2.0 g of an 80% by        weight ethanolic solution of diisopropyl triethanolamine        titanate (Tyzor TE, containing 8.2% by weight of Titanium) were        added in a diol/dicarboxylic acid molar ratio (MGR) of 1.20 to a        steel reactor having a geometrical capacity of 40 litres, fitted        with a mechanical stirrer system, an inlet for nitrogen, a        distillation column, a knock-down system for high-volume        distillates and a connection to a high vacuum system. The        temperature of the mass was gradually increased to 230° C. over        a period of 120 minutes. When 95% of the theoretical water had        been distilled off, 21.2 g (corresponding to 119 ppm of metal        with respect to the quantity of PBST which could theoretically        be obtained by converting all the sebacic acid and all the        terephthalic acid fed to the reactor) of tetra n-butyl Titanate        was added. The temperature of the reactor was then raised to        235-240° C. and the pressure was gradually reduced until a value        of less than 2 mbar was reached over a period of 60 minutes. The        reaction was allowed to proceed for the time required to obtain        a poly(1,4-butylene sebacate-co-1,4-butylene terephthalate) with        an MFR of approximately 5 (g/10 minutes at 190° C. and 2.16 kg),        and the material was then discharged in the form of a filament        into a water bath and granulated.

Component ii

-   -   ii=Ingeo 4043D polylactic acid (“PLA”), MFR 3.5/10min (at 190°        C., 2.16 kg).

Component iii

-   -   iii-1=HMV-15CA Carbodilite from Nisshinbo Chemical Inc.;    -   iii-2=Luperox F40MG        (1,3-1,4-bis(tert-butylperoxyisopropyl)-benzene in EPM rubber)        from Arkema;    -   iii-3=masterbatch comprising 10% by weight of Joncryl ADR4368CS        (styrene-glycidylether-methylmethacrylate copolymer) and 90% by        weight of component ii.

Component iv

-   -   iv=micronised talc having a median diameter of 1 microns        (particle size distribution by Sedigraph according to ISO        13317-3), Jetfine 3CA commercial grade from Imerys.

Examples 1-4 Production of Thermoformed Articles Comprising theComposition According to this Invention

TABLE 1 Compositions in Examples 1-4. Components (% wt) Example i-1 i-2ii iii-1 iii-2 iii-3 iv 1 47.7 — 16 0.2 36.1 2 42.7 5 16 0.2 36.1 3 47.7— 16 — 0.2 — 36.1 4 47.7 — 14.7 — — 1.5 36.1

The composition in Table 1 was fed to an Icma San Giorgio MCM 25 HTmodel co-rotating twin screw extruder under the following operatingconditions:

-   -   Screw diameter (D)=25 mm;    -   L/D=52;    -   Rotation speed=200 rpm;    -   Temperature profile=100-180-215×9-180-170-160° C.;    -   Throughput 10.1 kg/h;    -   Degassing under vacuum;

The granules were fed to a Curti single-screw extruder (screw diameter40 mm -L/D 25) equipped with a flat head 400 mm wide and Teknomastcompound rolling unit of 3 rolls of width 400 and diameter 200-andprovided with water cooling. The operating conditions were as follows:

-   -   Screw diameter (D)=40 mm;    -   L/D=25;    -   Rotation speed=60 rpm;    -   Temperature profile=Extruder: 190-5×200° C./Head: 6×200° C.;    -   Throughput20 kg/h.

From the sheets were obtained bars (length 30 mm, width 6 mm, thickness0.5 mm) which then underwent dynamic mechanical-torsional analysis(DMTA) in torsional mode using an Ares G2 rotational rheometer from TAInstrument. The samples were heated from 30° C. to 120° C. at 3° C./minimposing a deformation of 0.1% and a frequency of 1 Hz.

Heat deflection temperature (HDT) was measured according to standardASTM-D648 using a 0.455 MPa load (Method B), on moulded test specimensof the “bar” type (length 127 mm, width 12.7 mm, thickness 3.2 mm) usingCeast 6510 Test-A-Matic model equipment. HDT values were determined intriplicate for each composition. The value stated corresponds to thearithmetic mean of the measured values.

Sheets of 350 μm thickness were thermoformed on an Artpack thermoformingmachine in a single die mould for the production of plates (diameter 220mm, depth 40 mm) using the following thermoforming operating conditions:

-   -   Heating by means of 15 IR lamps (rated maximum power of each        lamp 325 W);    -   Heating time 5-8 sec. (to softening);    -   Total cycle time 15-20 sec.

The plates obtained underwent a disintegration test in controlledcomposting according to standard ISO20200:2004, showing a weight loss ofmore than 90% over 90 days at 58° C.

TABLE 2 HDT and DMTA characterization. Example HDT ° C. G′ [MPa] a T =70° C. G′ [MPa] a T = 90° C. 1 91 ± 1 471 374 2 91 ± 1 398 306 3 91 ± 1421 322 4 91 ± 1 349 238

1. A polymer composition for the production of thermoformed articlescomprising, with respect to the sum of components i.-iv.: i) 20-60% byweight of at least one polyester i. comprising: a) a dicarboxyliccomponent comprising with respect to the total dicarboxylic component:a1) 0-20% in moles of units deriving from at least one aromaticdicarboxylic acid, a2) 80-100% in moles of units deriving from at leastone saturated aliphatic dicarboxylic acid, a3) 0-5% in moles of unitsderiving from at least one unsaturated aliphatic dicarboxylic acid; b) adiol component comprising, with respect to the total diol component: b1)95-100% in moles of units deriving from at least one saturated aliphaticdiol; b2) 0-5% in moles of units deriving from at least one unsaturatedaliphatic diol; ii) 5-35% by weight of at least one polyhydroxyalkanoateii.; iii) 0.01-5% by weight of at least one cross-linking agent and/or achain extender iii. comprising at least one compound having di- and/ormultiple functional groups comprising isocyanate, peroxide,carbodiimide, isocyanurate, oxazoline, epoxy, anhydride, divinyl ethergroups and mixtures thereof; iv) 5-50% by weight of at least one mineralfiller agent present in the form of particles having a median diameterof less than 1.5 microns.
 2. The polymer composition according to claim1, in which the said at least one polyester i. comprises an aliphaticpolyester (AP), comprising a dicarboxylic component consisting of, withrespect to the total moles of the dicarboxylic component, 95-100% inmoles of units deriving from at least one saturated aliphaticdicarboxylic acid and 0-5% in moles of units deriving from at least oneunsaturated aliphatic dicarboxylic acid and a diol component comprising,with respect to the total moles of the diol component, 95-100% in molesof units deriving from at least one saturated aliphatic diol and 0-5% inmoles of units deriving from at least one unsaturated aliphatic diol. 3.The polymer composition according to claim 2, in which the saidaliphatic polyester (AP) is selected from the group consisting ofpoly(1,4-butylene succinate), poly(1,4-butylene adipate),poly(1,4-butylene azelate), poly(1,4-butylene sebacate),poly(4,1-butylene adipate-co-1,4-butylene succinate), poly(1,4-butyleneazelate-co-1,4-butylene succinate), poly(1,4-butylenesebacate-co-1,4-butylene succinate), and poly(1,4-butylenesuccinate-co-1,4-butylene adipate-co-1,4-butylene azelate).
 4. Thepolymer composition according to claim 1, in which the said aliphaticpolyester (AP) is poly(1,4-butylene succinate).
 5. The polymercomposition according to claim 1, in which the said at least onepolyhydroxyalkanoate ii. is selected from the group consisting ofpolyesters of lactic acid, poly-ε-caprolactone, polyhydroxybutyrate,polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate,polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate,polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate,polyhydroxybutyrate-ottadecanoate, and poly-3-hydroxybutyrate4-hydroxybutyrate.
 6. The polymer composition according to claim 1,wherein the said at least one mineral filler agent iv. is talc.
 7. Thepolymer composition according to claim 1, wherein the said mineralfiller agent is present in the form of particles having a mediandiameter of less than 1.2 microns.
 8. A thermoformed article comprisingthe polymer composition according to claim
 1. 9. The thermoformedarticle according to claim 8, selected from the group consisting of, aplate, a cup, a rigid container, a capsule for the dispensing of abeverage, a lid, a cover, or a container for food which can be heated ina conventional or microwave oven.
 10. The polymer composition accordingto claim 2, in which the said aliphatic polyester (AP) ispoly(1,4-butylene succinate).
 11. The polymer composition according toclaim 3, in which the said aliphatic polyester (AP) is poly(1,4-butylenesuccinate).
 12. The polymer composition according to claim 2, in whichthe said at least one polyhydroxyalkanoate ii. is selected from thegroup consisting of polyesters of lactic acid, poly-ε-caprolactone,polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyratepropanoate, polyhydroxybutyrate-hexanoate,polyhydroxybutyrate-decanoate, polyhydroxybutyrate-dodecanoate,polyhydroxybutyrate-esadecanoate, polyhydroxybutyrate-ottadecanoate, andpoly-3-hydroxybutyrate 4-hydroxybutyrate.
 13. The polymer compositionaccording to claim 3, in which the said at least onepolyhydroxyalkanoate ii. is selected from the group consisting ofpolyesters of lactic acid, poly-ε-caprolactone, polyhydroxybutyrate,polyhydroxybutyrate-valerate, polyhydroxybutyrate propanoate,polyhydroxybutyrate-hexanoate, polyhydroxybutyrate-decanoate,polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-esadecanoate,polyhydroxybutyrate-ottadecanoate, and poly-3-hydroxybutyrate4-hydroxybutyrate.
 14. The polymer composition according to claim 2,wherein the said at least one mineral filler agent iv. is talc.
 15. Thepolymer composition according to claim 3, wherein the said at least onemineral filler agent iv. is talc.
 16. The polymer composition accordingto claim 4, wherein the said at least one mineral filler agent iv. istalc.
 17. The polymer composition according to claim 5, wherein the saidat least one mineral filler agent iv. is talc.
 18. A thermoformedarticle comprising the polymer composition according to claim
 2. 19. Athermoformed article comprising the polymer composition according toclaim
 3. 20. A thermoformed article comprising the polymer compositionaccording to claim 4.